Effect of phase-shift step on hologram reconstruction in Fresnel incoherent correlation holography

Abstract

Fresnel Incoherent Correlation Holography (FINCH) enables holograms to be created from incoherent light illumination of 3D objects. The optical setup of FINCH is usually simple and compact owe to its in-line geometry while the reconstruction of hologram suffers from the obstruction of zero-order item and twin image. Phase-shift technology is combined with FINCH in order to obtain zero-order-free and twin-image-free reconstruction. Three-step phase-shifting is adopted in all the publications of FINCH and the application of other multi-step phase-shift technology in FINCH are not investigated yet. The Fresnel holograms are sequentially recorded with different multi-step phase-shifting (including four, three, and two-step) to form the complex hologram and the quality of the reconstructed images are compared by simulations and experiments respectively in this study. Several parameters including resolution, SNR and normalized cross-correlation are applied to evaluate the quality of reconstruction images. Although various noises would be introduced by the optical elements and the experimental environment in practice, four-step phase-shifting provides the best quality of the reconstructed image but the system resolution is not different from others. In addition, the influence of different phase shift plus to the quality of reconstruction images in the three-step phase-shifting FINCH is investigated and the results show that the quality of reconstruction images which use the π/2 is better than that 2π/3.